Micro-grid frequency stable operation control system under new energy access

Abstract

The invention provides a microgrid frequency stable operation control system under new energy access. The microgrid frequency stable operation control system comprises a photovoltaic power generation unit, a load unit, an energy storage unit, a power grid and a control unit, one ends of the photovoltaic power generation unit, the load unit and the energy storage unit are respectively connected with a power grid through a switch, and the other ends of the photovoltaic power generation unit, the load unit and the energy storage unit are respectively connected with the control unit; the control unit is used for generating a control instruction based on the frequency deviation of the power grid, the frequency deviation change rate of the power grid, the photovoltaic power generation power deviation of the photovoltaic power generation unit, the active power of the load unit and the charge state of the energy storage unit under the condition that the photovoltaic power generation unit, the load unit and the energy storage unit are connected or disconnected; the control instruction is used for adjusting the photovoltaic power generation power of the photovoltaic power generation unit, the load capacity of the load unit and the charging and discharging mode of the energy storage unit. The self-adaptive capability and the overall efficiency of the power system can be improved, and stable operation is ensured.

Description

Technical Field

[0001] This invention relates to the field of new energy power generation technology, and in particular to a microgrid frequency stability operation control system under new energy access. Background Technology

[0002] With the increasing penetration rate of renewable energy, renewable energy units have a significant impact on the transient characteristics of the system. When the system is subjected to external disturbances or faults, the grid voltage level drops rapidly and gradually recovers within a short period, which may last from several power frequency cycles to a few seconds. This short-term voltage drop can cause significant impacts on end-user equipment, such as process failures or shutdowns, resulting in substantial economic losses. In systems with renewable energy integration, the traditional practice is to trip the renewable energy units when a fault occurs, but for systems with a high proportion of renewable energy, this can exacerbate the power deficit and lead to system frequency instability. Renewable energy units inherently possess high and low voltage ride-through characteristics. When the system is subjected to disturbances or faults, photovoltaic units should be able to maintain grid-connected operation. The active power output of the photovoltaic inverter drops rapidly while simultaneously generating reactive power, thus providing support for the transient drop in bus voltage and maintaining system voltage and frequency stability to a certain extent. Summary of the Invention

[0003] This invention provides a microgrid frequency stability operation control system under new energy access, in order to overcome the defects existing in the prior art.

[0004] This invention provides a microgrid frequency stability operation control system under new energy access, comprising: Photovoltaic power generation unit, load unit, energy storage unit, power grid, and control unit; One end of each of the photovoltaic power generation unit, the load unit, and the energy storage unit is connected to the power grid via a switch, and the other end of each of the photovoltaic power generation unit, the load unit, and the energy storage unit is connected to the control unit. The control unit is used to generate control commands based on the frequency deviation of the power grid, the rate of change of the frequency deviation of the power grid, the photovoltaic power generation power deviation of the photovoltaic power generation unit, the active power of the load unit, and the state of charge of the energy storage unit when the photovoltaic power generation unit, the load unit, and the energy storage unit are off-grid or connected to the grid. The control commands are used to adjust the photovoltaic power generation power of the photovoltaic power generation unit, the load of the load unit, and the charging and discharging mode of the energy storage unit.

[0005] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided. The control unit is used to perform fuzzification processing on the frequency deviation, the frequency deviation change rate, the photovoltaic power generation deviation, the active power, and the state of charge respectively when the photovoltaic power generation unit, the load unit, and the energy storage unit are respectively off-grid or connected to the grid, to determine the fuzzy sets to which the frequency deviation, the frequency deviation change rate, the photovoltaic power generation deviation, the active power, and the state of charge belong, and to generate control commands based on the fuzzy sets to which the frequency deviation, the frequency deviation change rate, the photovoltaic power generation deviation, the active power, and the state of charge belong.

[0006] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided, wherein the fuzzy set of frequency deviation includes negative large, negative small, zero, positive small, and positive large; the fuzzy set of frequency deviation change rate includes negative large, negative small, zero, positive small, and positive large; the fuzzy set of photovoltaic power generation deviation includes negative large, negative small, zero, positive small, and positive large; the fuzzy set of active power includes negative large, negative medium, negative small, zero, positive small, positive medium, and positive large; and the fuzzy set of state of charge includes very low, low, medium, high, and very high.

[0007] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is high, the control command is used to increase the discharge rate of the energy storage unit by a first magnitude and reduce the first load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is low, the control command is used to increase the discharge rate of the energy storage unit and reduce the second load of the load unit by a second amplitude; the first amplitude is greater than the second amplitude; When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the third load amount of the load unit; the first load amount, the second load amount, and the third load amount increase sequentially.

[0008] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is zero, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load on the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is zero, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit.

[0009] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided. When the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit.

[0010] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively small or zero, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively small or zero, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0011] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0012] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and small or zero, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and small or zero, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0013] According to the present invention, a microgrid frequency stability operation control system under new energy access is provided. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is positive and small or positive and large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is positive and small or positive and large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0014] The microgrid frequency stability operation control system provided by this invention can flexibly respond to dynamic changes in the grid environment based on the grid frequency deviation, the grid frequency deviation change rate, the photovoltaic power generation deviation of the photovoltaic power generation unit, the active power of the load unit, and the state of charge of the energy storage unit. It can adjust the photovoltaic power generation of the photovoltaic power generation unit, the load of the load unit, and the charging and discharging mode of the energy storage unit, thereby improving the self-adaptability and overall efficiency of the power system and ensuring stable operation. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the microgrid frequency stability operation control system under new energy access provided by the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0018] When a fault occurs in a system after renewable energy is integrated, the traditional approach is to trip the renewable energy units due to the activation of protection devices. However, for systems with a high proportion of renewable energy, this can exacerbate the power deficit and lead to system frequency instability. Renewable energy units inherently possess high and low voltage ride-through characteristics. When the system is disturbed or a fault occurs, the photovoltaic units should be able to maintain grid-connected operation. The active power output of the photovoltaic inverter drops rapidly while simultaneously generating reactive power, thus providing support for the transient drop in bus voltage and maintaining system voltage and frequency stability to a certain extent.

[0019] In the context of high penetration rates of new energy sources being connected to the distribution network in existing technologies, the technical problem to be solved by this invention is how to ensure that photovoltaic units can operate in parallel with the grid and maintain the stability of the system frequency when the system is disturbed or malfunctions.

[0020] Figure 1 This is a schematic diagram of the microgrid frequency stability operation control system provided by the present invention under the new energy access, as shown below. Figure 1As shown, the system includes a photovoltaic power generation unit, a load unit, an energy storage unit, a power grid, and a control unit; One end of the photovoltaic power generation unit, the load unit, and the energy storage unit are connected to the power grid via switches, such as... Figure 1 As shown, the load unit is connected to the grid via switch K1, the photovoltaic power generation unit is connected to the grid via switch K2, and the energy storage unit is connected to the grid via switch K3. When switch K4 is closed, the system is in grid-connected mode; when switch K4 is open, the system is in islanded mode. In other words, this embodiment of the invention achieves free switching between the two operating modes of the system by connecting to the grid via switches. The switches can be circuit breaker switches.

[0021] In addition, the other ends of the photovoltaic power generation unit, load unit, and energy storage unit are respectively connected to the control unit. The control unit is used to generate control commands based on the grid frequency deviation, the grid frequency deviation change rate, the photovoltaic power generation deviation of the photovoltaic power generation unit, the active power of the load unit, and the state of charge of the energy storage unit when the photovoltaic power generation unit, load unit, and energy storage unit are off-grid or on-grid. The control commands are used to adjust the photovoltaic power generation of the photovoltaic power generation unit, the load of the load unit, and the charging and discharging mode of the energy storage unit.

[0022] The control unit may include a Distributed Control System (DCS) expert system. The DCS expert system may include a knowledge base, database, inference engine, interpreter, knowledge acquisition module, and user interface. The knowledge base stores performance data related to the photovoltaic system, characteristics of energy storage devices, load forecasting models, grid rules and standards, weather forecast information, and historical electricity consumption patterns. The database is used to collect real-time and historical data, such as the photovoltaic power generation of the photovoltaic power generation unit, the state of charge of the energy storage unit, and the active power of the load unit. The inputs to the DCS expert system may include frequency deviation Δf, the rate of change of frequency deviation Δdf, and the photovoltaic power generation deviation ΔP of the photovoltaic power generation unit. pv (i.e., the deviation between the output power of the photovoltaic power generation unit and the predicted output power), the state of charge (SOC) of the energy storage unit, and the active power (P) of the load unit. d For each input variable, define a series of fuzzy sets and their corresponding membership functions.

[0023] The inference engine processes information in the knowledge base based on fuzzy rules and algorithms, and, combined with real-time data collected from the database, issues control commands to adjust the photovoltaic power generation of the photovoltaic power generation unit, the load of the load unit, and the charging and discharging mode of the energy storage unit.

[0024] Furthermore, fuzzy control rules and intelligent algorithms can be set based on expert knowledge base and user experience, while continuously learning, improving, predicting, and adjusting control strategies based on historical data. The interpreter provides a human-machine interface to help users understand the reasons behind system commands. The knowledge acquisition module updates and maintains the knowledge base; this can be an automatic or semi-automatic process, including collecting new knowledge from experts or learning and integrating new information from system operation. The user interface allows users to interact with the system, input queries, set parameters, or adjust system settings.

[0025] Under normal system conditions, the photovoltaic power generation unit outputs active power P. pv The net active power P of the energy storage unit ES (Negative value during charging, positive value during discharging), Active power P consumed by the load unit. ld The active power Ps flowing into or out of the large power grid, and the active power supply and demand balance formula of the system are: P S =P pv +P ES -P ld

[0026] When system disturbances occur, such as sudden load changes or variations in renewable energy output, the DCS expert system monitors equipment data changes in real time. When the system experiences a large disturbance or a fault, protection devices activate, forming an isolated grid based on photovoltaic power generation units, energy storage units, and load units. The active power supply and demand balance formula is: 0 = P pv +P ES -P ld

[0027] In other words, the system has two operating modes: network mode and island mode. By connecting to the power grid through a switch, the system can freely switch between the two operating modes.

[0028] Furthermore, once the disturbance is eliminated, the DCS expert system guides the system back to normal operation, analyzes the cause of the disturbance, optimizes the control strategy, and forms expert knowledge and experience.

[0029] In a microgrid, the photovoltaic (PV) power generation unit is the renewable energy source, typically an array of solar photovoltaic panels that converts solar energy into direct current (DC) electricity. Load units are the energy-consuming components, potentially including homes, industrial equipment, or other facilities; their energy demands impact the overall system's operation. Energy storage units, usually implemented through battery systems, store excess energy or release it when needed, helping to balance the intermittent nature of PV power generation with the differences in load demand. The power grid is the primary source of electricity and the external power network the system can connect to and disconnect from. In microgrid operation, the grid can serve as a backup or primary power source. The control unit acts as the system's intelligent hub, monitoring and regulating energy flow between the PV power generation units, load units, and energy storage units to optimize system efficiency and stability.

[0030] The control unit generates control commands based on various factors, including the frequency deviation of the power grid (for synchronizing the grid connection status), the photovoltaic power generation deviation (for adjusting the photovoltaic power generation), the active power demand of the load unit (for balancing the load), and the charging and discharging status of the energy storage unit (for adjusting the operating mode of the energy storage device).

[0031] In addition, control commands are used to adjust the photovoltaic power generation of the photovoltaic power generation units, the load of the load units, and the charging and discharging modes of the energy storage units. In other words, the control unit can dynamically adjust photovoltaic power generation, load consumption, and energy storage operation to optimize the energy flow of the entire microgrid system and ensure system stability and efficiency.

[0032] Overall, the embodiments of the present invention can flexibly respond to dynamic changes in the power grid environment based on the frequency deviation of the power grid, the rate of change of the frequency deviation of the power grid, the photovoltaic power generation deviation of the photovoltaic power generation unit, the active power of the load unit, and the state of charge of the energy storage unit, thereby adjusting the photovoltaic power generation of the photovoltaic power generation unit, the load of the load unit, and the charging and discharging mode of the energy storage unit, thereby improving the adaptive capability and overall efficiency of the power system.

[0033] Based on the above embodiments, the control unit is used to perform fuzzification processing on frequency deviation, frequency deviation change rate, photovoltaic power deviation, active power and state of charge respectively when the photovoltaic power generation unit, load unit and energy storage unit are off-grid or connected to the grid, to determine the fuzzy sets to which the frequency deviation, frequency deviation change rate, photovoltaic power deviation, active power and state of charge belong respectively, and to generate control commands based on the fuzzy sets to which the frequency deviation, frequency deviation change rate, photovoltaic power deviation, active power and state of charge belong respectively.

[0034] Specifically, the frequency deviation refers to the difference between the actual frequency of the power grid and the standard frequency. The rate of change of frequency deviation is the rate at which the frequency deviation changes over time. The photovoltaic power deviation refers to the difference between the actual output power of the photovoltaic power generation unit and the expected output power. The active power refers to the power that the system is currently delivering to the load unit. The state of charge refers to the ratio between the current battery level of the energy storage unit and the total capacity.

[0035] In the system, when the photovoltaic power generation unit, the load unit, and the energy storage unit are off-grid or on-grid, the fuzzy sets to which the frequency deviation, the rate of change of frequency deviation, the photovoltaic power deviation, the active power, and the state of charge belong are determined through fuzzy processing. Finally, based on the judgments of these fuzzy sets, appropriate control instructions are generated to maintain the stable operation of the system in different states or to restore normal operation.

[0036] Among them, the fuzzy sets of the frequency deviation include negative large (NB), negative small (NS), zero (Z), positive small (PS), and positive large (PB); the fuzzy sets of the rate of change of frequency deviation include negative large (NB), negative small (NS), zero (Z), positive small (PS), and positive large (PB); the fuzzy sets of the photovoltaic power deviation include negative large (NB), negative small (NS), zero (Z), positive small (PS), and positive large (PB); the fuzzy sets of the active power include negative large (NB), negative medium (NM), negative small (NS), zero (Z), positive small (PS), positive medium (PM), and positive large (PB); the fuzzy sets of the state of charge include very low (VL), low (L), medium (M), high (H), and very high (VH).

[0037] As an optional embodiment, the fuzzy set of the frequency deviation Δf is defined as [negative large (NB), negative small (NS), zero (Z), positive small (PS), positive large (PB)].

[0038] For an input variable x ∈ PB of the frequency deviation Δf, when x ≤ 0, μf(x) = 0, that is, when the input variable x is less than or equal to 0, it does not belong to the set PB; when 0 < x < Δfmax, μf(x) is a linearly increasing function, which can be set as μf(x) = x / Δfmax; when x ≥ Δfmax, μf(x) = 1.

[0039] For an input variable x ∈ PS of the frequency deviation Δf, when x ≤ 0, μf(x) = 0, that is, when the input variable x is less than or equal to 0, it does not belong to the set PS; when 0 < x < Δfmax or x ≥ Δfmax, μf(x) = 1.

[0040] For an input variable x ∈ Z of the frequency deviation Δf, when x = 0, μf(x) = 1, and when x ≠ 0, μf(x) = 0.

[0041] For a frequency deviation Δf and an input variable x∈NB, when x≥0, μf(x)=0, that is, when the input variable x is greater than or equal to 0, it does not belong to the set NB; when 0>x>-Δfmax, μf(x) is a linearly increasing function, which can be set as μf(x)=|x| / Δfmax; when x≤-Δfmax, μf(x)=1.

[0042] For a frequency deviation Δf and an input variable x ∈ NS, when x ≥ 0, μf(x) = 0, that is, when the input variable x is greater than or equal to 0, it does not belong to the set NS; when 0 > x > -Δfmax or x ≤ -Δfmax, μf(x) = 1.

[0043] Furthermore, the fuzzy set of the frequency deviation change rate Δdf is defined as [negative large (NB), negative small (NS), zero (Z), positive small (PS), positive large (PB)].

[0044] For the rate of change of frequency deviation Δdf, which is an input variable x∈Z, when x=0, μf(x)=1, and when x≠0, μf(x)=0.

[0045] Similar to the fuzzy set with frequency deviation Δf, for an input variable x with input Δdf, the membership function of the fuzzy set for different fuzzy values ​​is:

[0046] Based on historical data collection experience, the fuzzy relationship between the membership function parameters and Δdf for different fuzzy values ​​is identified. During program operation, Δdf is continuously detected, and the membership function parameters are modified online according to the fuzzy control principle to meet the different requirements of different Δdf for control parameters.

[0047] Furthermore, the fuzzy set of the state of charge (SOC) of the energy storage unit is defined as [Very Low (VL), Low (L), Medium (M), High (H), Very High (VH)].

[0048] For an energy storage unit given a State of Charge (SOC) value, the fuzzy value is VL when SOC < 20%; L when 20% ≤ SOC < 40%; M when 40% ≤ SOC < 60%; H when 60% ≤ SOC < 80%; and VH when 80% ≤ SOC.

[0049] Furthermore, the photovoltaic power generation deviation ΔP is defined. pv The fuzzy set is [negative large (NB), negative small (NS), zero (Z), positive small (PS), positive large (PB)].

[0050] For photovoltaic power generation deviation ΔP pv Given an input variable x∈Z, when x=0, μf(x)=1, and when x≠0, μf(x)=0.

[0051] For ΔP pv Given an input variable x, its membership function for different fuzzy values ​​of a fuzzy set is:

[0052] Based on historical data collection experience, the membership function parameters and ΔP for different fuzzy values ​​were identified. pv The fuzzy relationship between them is determined by continuously detecting ΔP during program execution. pv Based on the principle of fuzzy control, the membership function parameters are modified online to satisfy different ΔP values. pv Different requirements for control parameters.

[0053] Furthermore, the active power P of the load unit is defined. d The fuzzy set is [Negative Large (NB), Negative Medium (NM), Negative Small (NS), Zero (Z), Positive Small (PS), Positive Medium (PM), Positive Large (PB)].

[0054] Furthermore, for P d Given an input variable x, its membership function for different fuzzy values ​​of a fuzzy set is:

[0055] Furthermore, based on historical data collection experience, the membership function parameters for different fuzzy values ​​and P are identified. d The fuzzy relationship between them is resolved by continuously detecting P during program execution. d Based on the principle of fuzzy control, the membership function parameters are modified online to meet the needs of different P... d Different requirements for control parameters.

[0056] Optionally, the above input variables are fuzzified to obtain the following fuzzy set universe of discourse:

[0057] Correspondingly, the output of the aforementioned DCS expert system is control commands, including photovoltaic active power adjustment commands (used to adjust the photovoltaic power generation of the photovoltaic power generation unit), load adjustment commands (used to adjust the load of the load unit), and energy storage charging and discharging commands (used to adjust the charging and discharging mode of the energy storage unit).

[0058]

[0059] The fundamental universe of discourse for the fuzzy output quantity mentioned above is as follows: For SOC es.outThe fuzzy set NB / NS represents the charging state, the fuzzy set PB / PS represents the discharging state, and 0 represents the exit from operation state. Furthermore, the fuzzy output quantities are defuzzified and converted into explicit digital signal commands, including energy storage system charging and discharging commands, photovoltaic unit active and reactive power adjustment quantities, and load increase or decrease quantities, to compensate for frequency deviations.

[0060] Overall, the fuzzy intelligent control algorithm based on photovoltaics, energy storage, and load in the embodiments of the present invention can flexibly respond to dynamic changes in the power grid environment, such as fluctuations in photovoltaic output, changes in energy storage status, and uncertainties in load demand, balance instantaneous power supply and demand differences, thereby improving the adaptive capability and overall efficiency of the power system.

[0061] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is high, the control command is used to increase the discharge rate of the energy storage unit by a first magnitude and reduce the first load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is low, the control command is used to increase the discharge rate of the energy storage unit and reduce the second load of the load unit by a second amplitude; the first amplitude is greater than the second amplitude; When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the third load amount of the load unit; the first load amount, the second load amount, and the third load amount increase sequentially.

[0062] Optionally, when Δf∈NB and Δdf∈NB, if the state of charge is high (H), the energy storage discharge rate should be increased by a relatively large amount (e.g., the first amount) while simultaneously executing a load reduction command (i.e., reducing the first load amount of the load unit); if the state of charge is low (L), the energy storage discharge rate should be increased appropriately (i.e., the discharge rate of the energy storage unit should be increased by a second amount) while simultaneously executing a load reduction command (i.e., reducing the second load amount of the load unit); if the state of charge is very low (VL), a large load reduction command should be executed (i.e., reducing the third load amount of the load unit), that is: If Δf∈NB and Δdf∈NB and SOC∈VH or H, then SOC es.out =PB, P load.out =PS; If Δf∈NB and Δdf∈NB and SOC∈M or L, then SOC es.out =PS,P load.out =PM;; If Δf∈NB and Δdf∈NB and SOC∈VL, then P load.out =PB.

[0063] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit; when the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit.

[0064] When Δf∈NB and Δdf∈NS, if the state of charge (VL) is very low, a load shedding command should be executed (i.e., the load amount of the load unit should be reduced). Conversely, if the state of charge is high, the energy storage discharge rate should be appropriately increased while executing the load shedding command (increasing the discharge rate of the energy storage unit and reducing the load amount of the load unit), that is: If Δf∈NB and Δdf∈NS and SOC∈VL, then P load.out =PM; if Δf∈NB and Δdf∈NS and SOCVL, then SOC es.out =PS,P load.out =PM.

[0065] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is zero, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit; when the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is zero, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit.

[0066] When Δf∈NB and Δdf∈0, if the state of charge (VL) is very low, a load reduction command should be executed (i.e., the load amount of the load unit should be reduced). Conversely, the energy storage discharge rate should be appropriately increased while executing the load reduction command (i.e., the discharge rate of the energy storage unit should be increased and the load amount of the load unit should be reduced).

[0067] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit.

[0068] When Δf∈NB and Δdf∈PS or PB, if the state of charge (VL) is very low, a load reduction command should be executed (i.e., the load amount of the load unit should be reduced). Conversely, the energy storage discharge rate should be appropriately increased (i.e., the discharge rate of the energy storage unit should be increased).

[0069] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit; when the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit.

[0070] When Δf∈NS and Δdf∈NB, if the state of charge (VL) is very low, a load reduction command should be executed (i.e., the load amount of the load unit should be reduced). Conversely, the energy storage discharge rate should be increased while the load reduction command is executed (i.e., the discharge rate of the energy storage unit is increased and the load amount of the load unit is reduced).

[0071] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit; when the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit.

[0072] When Δf∈NS and Δdf∈NS, if the state of charge (VL) is very low, a load reduction command should be executed (i.e., the load amount of the load unit should be reduced). Conversely, the energy storage discharge rate should be appropriately increased (i.e., the discharge rate of the energy storage unit should be increased).

[0073] When Δf∈NS and Δdf∈0, the active power of the system does not need to be adjusted, and the energy storage charging and discharging state remains unchanged.

[0074] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0075] When Δf∈PS and Δdf∈NB, if SOCH or VH, the energy storage unit enters charging mode until SOC∈H, and then executes the load increase command or the photovoltaic active power output decrease command (i.e., increase the load of the load unit or decrease the photovoltaic power generation of the photovoltaic power generation unit); if SOC∈H or VH, the energy storage unit exits operation and executes the load increase command or the photovoltaic active power output decrease command (i.e., increase the load of the load unit or decrease the photovoltaic power generation of the photovoltaic power generation unit).

[0076] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively small or zero, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively small or zero, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0077] When Δf∈PS and Δdf∈NS or 0, if SOCH or VH, the energy storage unit enters charging mode until SOC∈H, and then executes the appropriate load increase command or the appropriate reduction of photovoltaic active power output (i.e., increasing the load of the load unit or reducing the photovoltaic power generation of the photovoltaic power generation unit); if SOC∈H or VH, the energy storage unit exits operation and executes the appropriate load increase command or the appropriate reduction of photovoltaic active power output (i.e., increasing the load of the load unit or reducing the photovoltaic power generation of the photovoltaic power generation unit).

[0078] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0079] When Δf∈PS and Δdf∈PS or PB, if SOCH or VH, the energy storage unit enters charging mode until SOC∈H, and then executes the appropriate load increase command or the appropriate reduction of photovoltaic active power output (i.e., increasing the load of the load unit or reducing the photovoltaic power generation of the photovoltaic power generation unit); if SOC∈H or VH, the energy storage unit exits operation and executes the appropriate load increase command or the appropriate reduction of photovoltaic active power output (i.e., increasing the load of the load unit or reducing the photovoltaic power generation of the photovoltaic power generation unit).

[0080] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is positive and the fuzzy set to which the frequency deviation change belongs is negative and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0081] When Δf∈PB and Δdf∈NB, if SOCH or VH, the energy storage unit enters charging mode until SOC∈H, and then executes the load increase command or reduces the photovoltaic active power output (i.e., increases the load of the load unit or reduces the photovoltaic power generation of the photovoltaic power generation unit); if SOC∈H or VH, the energy storage unit exits operation and executes the load increase command or reduces the photovoltaic active power output (i.e., increases the load of the load unit or reduces the photovoltaic power generation of the photovoltaic power generation unit).

[0082] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and small or zero, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and small or zero, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0083] When Δf∈PB and Δdf∈NS or 0, if SOC ∈ H or VH, the energy storage unit enters charging mode until SOC∈H, and then executes the load increase command or reduces the photovoltaic active power output (i.e., increases the load of the load unit or reduces the photovoltaic power generation of the photovoltaic power generation unit); if SOC∈H or VH, the energy storage unit exits operation and executes the load increase command or appropriately reduces the photovoltaic active power output (i.e., increases the load of the load unit or reduces the photovoltaic power generation of the photovoltaic power generation unit).

[0084] Based on any of the above embodiments, when the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is positive and small or positive and large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is positive and small or positive and large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

[0085] When Δf∈PB and Δdf∈PS or PB, if SOCH or VH, the energy storage unit enters charging mode until SOC∈H, and then executes the load increase command or reduces the photovoltaic active power output (i.e., increases the load of the load unit or reduces the photovoltaic power generation of the photovoltaic power generation unit); if SOC∈H or VH, the energy storage unit exits operation and executes the load increase command or significantly reduces the photovoltaic active power output (i.e., increases the load of the load unit or reduces the photovoltaic power generation of the photovoltaic power generation unit).

[0086] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microgrid frequency stability operation control system under new energy access, characterized in that, include: Photovoltaic power generation unit, load unit, energy storage unit, power grid, and control unit; One end of each of the photovoltaic power generation unit, the load unit, and the energy storage unit is connected to the power grid via a switch, and the other end of each of the photovoltaic power generation unit, the load unit, and the energy storage unit is connected to the control unit. The control unit is used to generate control commands based on the frequency deviation of the power grid, the rate of change of the frequency deviation of the power grid, the photovoltaic power generation power deviation of the photovoltaic power generation unit, the active power of the load unit, and the state of charge of the energy storage unit when the photovoltaic power generation unit, the load unit, and the energy storage unit are off-grid or connected to the grid. The control commands are used to adjust the photovoltaic power generation power of the photovoltaic power generation unit, the load of the load unit, and the charging and discharging mode of the energy storage unit.

2. The microgrid frequency stability operation control system under new energy access according to claim 1, characterized in that, The control unit is used to perform fuzzification processing on the frequency deviation, the frequency deviation change rate, the photovoltaic power generation deviation, the active power, and the state of charge respectively, when the photovoltaic power generation unit, the load unit, and the energy storage unit are connected to the grid or disconnected from the grid, to determine the fuzzy sets to which the frequency deviation, the frequency deviation change rate, the photovoltaic power generation deviation, the active power, and the state of charge belong, and to generate control commands based on the fuzzy sets to which the frequency deviation, the frequency deviation change rate, the photovoltaic power generation deviation, the active power, and the state of charge belong.

3. The microgrid frequency stability operation control system under new energy access according to claim 2, characterized in that, The fuzzy set of frequency deviation includes negative large, negative small, zero, positive small, and positive large; the fuzzy set of frequency deviation change rate includes negative large, negative small, zero, positive small, and positive large; the fuzzy set of photovoltaic power generation deviation includes negative large, negative small, zero, positive small, and positive large; the fuzzy set of active power includes negative large, negative medium, negative small, zero, positive small, positive medium, and positive large; and the fuzzy set of state of charge includes very low, low, medium, high, and very high.

4. The microgrid frequency stability operation control system under new energy access according to claim 3, characterized in that, When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is high, the control command is used to increase the discharge rate of the energy storage unit by a first magnitude and reduce the first load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is low, the control command is used to increase the discharge rate of the energy storage unit and reduce the second load of the load unit by a second amplitude; the first amplitude is greater than the second amplitude; When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the third load amount of the load unit; the first load amount, the second load amount, and the third load amount increase sequentially.

5. The microgrid frequency stability operation control system under new energy access according to claim 3, characterized in that, When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load on the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is zero, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load on the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is zero, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively large, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit.

6. The microgrid frequency stability operation control system under new energy access according to claim 3, characterized in that, When the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit and reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very low, the control command is used to reduce the load of the load unit. When the fuzzy set to which the frequency deviation belongs is negatively small, the fuzzy set to which the frequency deviation change belongs is negatively small, and the fuzzy set to which the state of charge belongs is very high, the control command is used to increase the discharge rate of the energy storage unit.

7. The microgrid frequency stability operation control system under new energy access according to claim 3, characterized in that, When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively small or zero, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is negatively small or zero, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positively small, the fuzzy set to which the frequency deviation change belongs is positively small or positively large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

8. The microgrid frequency stability operation control system under new energy access according to claim 3, characterized in that, When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

9. The microgrid frequency stability operation control system under new energy access according to claim 3, characterized in that, When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and small or zero, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is negative and small or zero, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

10. The microgrid frequency stability operation control system under new energy access according to claim 3, characterized in that, When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is positive and small or positive and large, and the fuzzy set to which the state of charge belongs is not high or very high, the control command is used to control the energy storage unit to enter the charging mode until the fuzzy set to which the state of charge belongs is high, and then increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit. When the fuzzy set to which the frequency deviation belongs is positive and large, the fuzzy set to which the frequency deviation change belongs is positive and small or positive and large, and the fuzzy set to which the state of charge belongs is high or very high, the control command is used to control the energy storage unit to exit operation and increase the load of the load unit or reduce the photovoltaic power generation of the photovoltaic power generation unit.

Images